I have a 97 GMC 3500 with a 5.7. It has sat for 8 years I have replaced the starter,fule tank,fule pump,cap,rotor,plugs, and wire's. I have spark but it just seams to turn over real slow. The truck was running when parked. 8 years ago. Any help will be very helpful at this point I am all ears.

 

try disconnecting your main drive belt and turning the engine over and see if it cranks faster.check your alternator to see if its seizing up and anything else pulley related.are you getting fuel into the engine ,can you smell fuel.if it cranks over to slow it may not fire.